RESUMO
Objective:To study the clinical phenotype and molecular genetic characteristics of a Chinese Han family with X-linked retinoschisis (XLRS), and to determine the associated gene variations.Methods:A pedigree investigation was performed.The clinical characteristics and pedigree analysis of a Han Chinese family line with XLRS was conducted in August 2021 at the Xiamen Eye Center Affiliated to Xiamen University.All patients and the carriers underwent comprehensive medical history collection and routine ophthalmological examinations, including visual acuity, non-contact tonometer, slit lamp microscope, direct ophthalmoscope, and optical coherence tomography.The proband and some patients underwent medical optometry, fundus photography or wide-angle fundus photography, and electroretinogram examination.Peripheral venous blood samples were collected from the family members, and whole exome sequencing (WES) analysis was performed on the proband samples.For variants screened by WES, the expanded verification in other patients and normal persons in the family was carried out by Sanger sequencing.Multiple bioinformatic tools were used to analyze the pathogenicity of variants.This study protocol was approved by the Ethics Committee of Xiamen Eye Center of Xiamen University (No.XMYKZX-KY-2021-012). Written informed consent forms were obtained from each subject or guardian of minors.CADD, FATHMM and other bioinformatics tools were used to analyze the pathogenicity of the variation sites.Results:The Han XLRS pedigree consisted of 8 individuals in 3 generations.Out of the 3 cases diagnosed with XLRS based on clinical evaluation, all were male.The mother of the proband was a carrier of related genes.There were 5 persons with normal phenotypes.There was no history of consanguineous marriages within the family, and the disease was shown to be intergenerational, which is consistent with the recessive inheritance of the X chromosome.None of the patients had a history of systemic disease or any other abnormal manifestations.The prevailing feature of ophthalmopathy was poor binocular vision since childhood.The proband and his younger brother had spoke split in the macula, and their grandfather showed atrophy of retinal nerve fibers.Genetic analysis revealed a hemizygous variation c. 214G>C: p.Glu72Gln in the RS1 gene in all the patients in this family.The proband's mother was heterozygous at this site, and all other phenotypically normal family members exhibited wild type at this site.This variant was predicted to be a deleterious variation and likely to cause disease based on bioinformatics analysis. Conclusions:The proband and patients in this Han Chinese family have the known c. 214G>C: p.Glu72Gln hemizygous variation of the RS1 gene and exhibit mild XLRS, which was consistent with the recessive inheritance of X chromosome.
RESUMO
Objective:To study the characteristics of the genotype and phenotypic in a family with X-linked retinoschisis (XLRS) due to RS1 mutation. Methods:A retrospective clinical study. An XLRS family of 4 generations of 26 people were included in the study. Among them, 8 participants were males and 7 participants were females. Routine ophthalmologic examination was performed on 3 patients in the family including the proband and 12 patients with normal phenotype. Optical coherence tomography was performed in 2 of the 3 patients. Peripheral venous blood was extracted from all participants, whole-genome DNA was extracted, and potential pathogenic genes were screened by Panel sequencing. Conservative analysis, pathogenicity analysis and protein structure prediction were carried out by software tools. The pathogenicity of gene mutations was analyzed according to the American Society of Medical Genetics and Genomics (ACMG) guidelines.Results:The proband was 3 years old. Optical coherence tomography (OCT) examination showed that the retinal core layer in the macular area of both eyes had a cystic change, which was segmented by vertical or oblique bridging tissue. The proband's uncle was 32 years old. OCT examination showed atrophy in the macular area of the left eye. The macular area of the right eye was cystoid, segmented by vertical or oblique bridging tissue. No abnormality was found in the fundus examination of the proband's parents and 10 members of his family. Panel sequencing showed that c.361C>T/ p.Q121X hemizygous mutation was found in the fifth exon of RS1 gene in the proband (Ⅳ3) and 2 patients (Ⅱ1, Ⅲ8). The mother was a heterozygous mutation carrier of the gene, while the father had no mutation. The mutant gene causes premature termination of RS1, a truncated protein encoding 224 amino acids to 120 amino acids. Of the 10 patients with normal fundus examination, 6 participants were normal. The mutation was carried by four people, which were women. Homology analysis of the protein sequence showed that the mutant site was highly conserved in 12 mammals. Three-dimensional structural analysis of RS1 protein showed that the c-terminal amino acid sequence of the mutant protein was more than 50% missing. Analysis of ACMG guidelines indicated that the mutation was pathogenic. Conclusion:The RS1 mutation site c.361C>T/p.Q121X is a new mutation site of XLRS.